1. Field of the Invention
The present invention relates to a dye laser using dyes as laser materials. Particularly, it is concerned with a laser system for emitting laser beams of various wavelengths.
2. Description of the Prior Art
FIG. 1 illustrates a conventional multi-wavelength laser system which is shown for example in "Optics Communications," Vol. 7 (1973), p. 233. In the figure, the numeral 101 denotes a light transmitting, dye vessel which contains a dye solution 101A consisting of a dye as a laser material and a solvent; numeral 102 denotes an output mirror which not only outputs laser beams of wavelengths .lambda..sub.1 ' and .lambda..sub.2 ' but also is used in an optical resonance system; numeral 103 denotes a beam splitter disposed on a side opposite to the side where the output mirror 102 is located with respect to the dye vessel 101; numeral 104 denotes a diffraction grating disposed in a position where it receives light wave reflected by the beam splitter 103 and reflects diffractively a light wave portion of wavelength .lambda..sub.1 ' selectively at a high reflectance; and numeral 105 denotes a diffraction grating disposed in a position where it receives light wave which has passed through the beam splitter 103 and reflects diffractively a light wave portion of wavelength .lambda..sub.2 ' selectively at a high reflectance. If necessary, a polarizer, ND filter, or beam expander, is disposed between the beam splitter 103 and the diffraction grating 104 and between the beam splitter 103 and the diffraction grating 105. An optical resonator for the light wave of wavelength .lambda..sub.1 ' is constituted by the dye vessel 101 containing the dye solution 101A, output mirror 102, beam splitter 103 and diffraction grating 104, while an optical resonator for the light wave of wavelength .lambda..sub.2 ' is constituted by the dye vessel 101 containing the dye solution 101A, output mirror 102, beam splitter 103 and diffraction grating 105.
The operation of the above conventional laser system will now be described. A pumping light 106 emitted from a pumping light source (not shown) and condensed through an optical system (not shown) irradiates the dye solution A in the dye vessel 101. As a result, the dye in the dye solution 101A assumes a state of population inversion and a light wave of a specific wavelength region is generated from the dye. The diffraction grating 104 is turned and adjusted for the light wave incident thereon so that the reflectance of the light wave of wavelength .lambda..sub.1 ' becomes maximum, while the diffraction grating 105 is turned and adjusted for the light wave incident thereon so that the reflectance of the light wave of wavelength .lambda..sub.2 ' becomes maximum. The light wave of wavelength .lambda..sub.1 ' is generated as a laser beam by the above optical resonator comprising the components from the output mirror 102 up to the diffraction grating 104, while the light wave of wavelength .lambda..sub.2 ' is generated as a laser beam by the above optical resonator comprising the components from the output mirror 102 up to the diffraction grating 105. The light waves of wavelength .lambda..sub.1 ' and .lambda..sub.2 ' are output from the output mirror 102 as laser beams having wavelengths .lambda..sub.1 ' and .lambda..sub.2 ' respectively.
Since the conventional laser system for generating multi-wavelength light waves is constructed as above, the wavelength region of light waves capable of being generated is determined by a single dye solution in a single dye vessel and it is only about 80 nm at most (the difference between the wavelengths .lambda..sub.1 ' and .lambda..sub.2 ' being within about 80 nm). Besides, since light waves of plural wavelengths are generated by the same dye solution, the interaction between the generated light waves is strong due to pull-in phenomenon, thus making it impossible to obtain stable output power, output waveform and generation timing. Further, because of use of a beam splitter, the loss of light waves generated is large and therefore a laser beam of a sufficient intensity is not obtainable.